Loughborough Lightning 174 for 7 (Villani 61*, Haynes 53) beat Southern Vipers 172 for 6 (McGlashan 55*) by three wickets
Aussie stars Rachael Haynes and Elyse Villani powered Loughborough Lightning to a fifth win in six matches to stretch their lead at the top of the Women's Kia Super League and make their qualification for Finals Day look almost a formality.
Haynes posted her second half-century of the competition before, in a dramatic finish, Villani crashed four and six off New Zealand all-rounder Suzie Bates after Lightning, chasing a challenging 173 to win, had gone into the last over still needing 11 more runs.
Lightning had lost two wickets in the penultimate over as Jenny Gunn holed out to long-off and Lucy Higham was run out, but Villani kept her nerve to finish unbeaten on 61 after lofting Bates for a towering maximum backward of square to complete victory with two balls to spare.
It was tough luck on Vipers, last year's runners-up and the 2016 champions, who produced their best batting performance of the series in a bid to end a run of four straight defeats and keep alive their hopes of reviving their season.
Vipers veteran Sara McGlashan posted her highest KSL score with some powerful striking in an unbeaten 55 off just 28 deliveries, including six fours and three sixes, with England's Danni Wyatt weighing in with 34 as Vipers justified skipper Bates's decision to bat first by recording their biggest score of the season.
Lightning's hopes of limiting their opponents to a much lower total were high after Vipers lost their two most dangerous batters for single-figure scores inside the powerplay were dismissed both Bates and Tammy Beaumont for single-figure scores inside the powerplay overs.
Bates was caught on the mid-wicket boundary when she tried to go after Gunn, then Beaumont, back in the Vipers side after missing two matches because of a concussion injury, top-edged a pull-shot against Sophie Devine, Sarah Glenn safely pouching the catch.
Wyatt and Mignon du Preez added 39 for the third wicket yet after Wyatt had holed out off a Glenn full toss in the 10th over and Du Preez had pulled a short ball from Georgia Elwiss straight to mid-wicket in the 13th, Vipers had lost their top-four batters for 83.
But McGlashan took charge immediately, punishing former teammate Linsey Smith with four boundaries in an over as the left-arm spinner's customary control deserted her.
A nightmare over from Gunn cost 16 runs as the England seamer conceded 11 in wides, including five from each of two consecutive deliveries.
Smith was on the receiving end again as Arran Brindle struck three fours in an over and though Elwiss broke the partnership when she trapped Brindle in front for 26 in the penultimate over, the pair had added 71 in 7.2 overs.
McGlashan, the former New Zealand batter and wicket-keeper who retired from international cricket in 2016, finished with a flourish, smiting three huge sixes and a four off the last seven balls she faced, her second maximum off Devine's last over completing her half-century from the final ball of the innings.
Devine was an early casualty as Lightning began their reply but Haynes out on a display of high quality strokeplay and controlled power at the top of the innings.
Haynes made 53 off 34 balls and shared a partnership with Amy Jones that helped Lightning to 55 for 1 in the powerplay, laying the foundation for victory.
Jones fell for 31 from 18 balls, after which the onus rested on Villani's shoulders to put her experience to good use.
But she was well supported by her partners, who thwarted Vipers' best efforts to keep Villani off strike and in the end her aggressive hitting, which brought her seven fours and two sixes, made sure her compatriot Haynes' efforts did not go to waste as Lightning celebrated a third win in five days at the Haslegrave Ground.